org.apache.zookeeper.server.quorum

Class LearnerHandler

java.lang.Object

java.lang.Thread

org.apache.zookeeper.server.ZooKeeperThread

org.apache.zookeeper.server.quorum.LearnerHandler

All Implemented Interfaces:

Runnable

public class LearnerHandler
extends ZooKeeperThread

There will be an instance of this class created by the Leader for each learner. All communication with a learner is handled by this class.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
static String	FORCE_SNAP_SYNC For testing purpose, force leader to use snapshot to sync with followers
protected long	sid ZooKeeper server identifier of this learner
protected Socket	sock
protected int	version

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Method Summary

Modifier and Type	Method and Description
QuorumPeer.LearnerType	getLearnerType()
Queue<QuorumPacket>	getQueuedPackets() For testing, return packet queue
Socket	getSocket()
static String	packetToString(QuorumPacket p)
void	ping() ping calls from the leader to the peers
protected long	queueCommittedProposals(Iterator<Leader.Proposal> itr, long peerLastZxid, Long maxZxid, Long lastCommittedZxid) Queue committed proposals into packet queue.
void	run() This thread will receive packets from the peer and process them and also listen to new connections from new peers.
void	setFirstPacket(boolean value) For testing, we need to reset this value
void	shutdown()
protected void	startSendingPackets() Start thread that will forward any packet in the queue to the follower
boolean	synced()
boolean	syncFollower(long peerLastZxid, ZKDatabase db, Leader leader) Determine if we need to sync with follower using DIFF/TRUNC/SNAP and setup follower to receive packets from commit processor
long	tickOfNextAckDeadline()
String	toString()

Methods inherited from class org.apache.zookeeper.server.ZooKeeperThread

handleException

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, yield

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

sock

protected final Socket sock

sid

protected long sid

ZooKeeper server identifier of this learner

version

protected int version

FORCE_SNAP_SYNC

public static final String FORCE_SNAP_SYNC

For testing purpose, force leader to use snapshot to sync with followers

See Also:

Constant Field Values

Method Detail

getSocket

public Socket getSocket()

toString

public String toString()

Overrides:

toString in class Thread

getLearnerType

public QuorumPeer.LearnerType getLearnerType()

packetToString

public static String packetToString(QuorumPacket p)

run

public void run()

This thread will receive packets from the peer and process them and also listen to new connections from new peers.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

startSendingPackets

protected void startSendingPackets()

Start thread that will forward any packet in the queue to the follower

syncFollower

public boolean syncFollower(long peerLastZxid,
                            ZKDatabase db,
                            Leader leader)

Determine if we need to sync with follower using DIFF/TRUNC/SNAP and setup follower to receive packets from commit processor

Parameters:

peerLastZxid -

db -

leader -

Returns:

true if snapshot transfer is needed.

queueCommittedProposals

protected long queueCommittedProposals(Iterator<Leader.Proposal> itr,
                                       long peerLastZxid,
                                       Long maxZxid,
                                       Long lastCommittedZxid)

Queue committed proposals into packet queue. The range of packets which is going to be queued are (peerLaxtZxid, maxZxid]

Parameters:

itr - iterator point to the proposals

peerLastZxid - last zxid seen by the follower

maxZxid - max zxid of the proposal to queue, null if no limit

lastCommittedZxid - when sending diff, we need to send lastCommittedZxid on the leader to follow Zab 1.0 protocol.

Returns:

last zxid of the queued proposal

shutdown

public void shutdown()

tickOfNextAckDeadline

public long tickOfNextAckDeadline()

ping

public void ping()

ping calls from the leader to the peers

synced

public boolean synced()

getQueuedPackets

public Queue<QuorumPacket> getQueuedPackets()

For testing, return packet queue

Returns:

setFirstPacket

public void setFirstPacket(boolean value)

For testing, we need to reset this value